The present invention relates generally to a system and method for analyzing functional imaging data to determine indicators of various pathologies with increased speed and accuracy. More particularly, the present invention relates to a system and method for evaluating a full spectrum of functional imaging data, such as cardiac ultrasound images or entire echocardiogram waveforms, to determine indicators of pathologies such as ischemia.
Functional imaging has traditionally included such modalities as ultrasound and nuclear imaging systems, including positron emission tomography (PET) systems and single photon emission computed tomography (SPECT) systems. In recent years, additional techniques have evolved, such as functional magnetic resonance imaging (fMRI), tagged MRI, and magnetoencephalography (MEG). Furthermore, echocardiograms have been utilized as another feedback component that can be used alone or in combination with these functional imaging techniques.
Heart disease has a very high incidence as well as a high rate of early mortality. The use of functional imaging systems and, in particular, echocardiography has become widespread as a diagnosis tool for identifying symptoms of heart disease. For example, the real-time nature of echocardiograms has allowed for the observation of myocardial motion and its synchronicity or the lack thereof. Furthermore, Doppler analysis has been indirectly used with various functional imaging systems to analyze heart valve function by measuring blood flow and observing turbulence.
Continual advancements in these functional imaging systems have enabled the identification of symptoms of heart disease or other ailments. For example, new analysis techniques have been developed that help identify changes in cardiac function (cyclic cardiac muscle deformations) in disease. In particular, by analyzing echocardiogram waveforms obtained before and after ischemia, physicians and technicians have been able to identify features within echocardiogram waveforms that are indicative of altered myocardial deformations. These alterations can then be related to disease symptoms or pathologies.
However, due to the complexity and variability of these waveforms in both normal hearts at their baseline condition and in the same hearts after occlusion of a coronary artery, the evaluation and analysis of these waveforms is extremely intensive and requires highly skilled determinations to be made in real or near real-time. Hence, a physician or technician must evaluate a baseline echocardiogram waveform and compare it to an echocardiogram waveform following ischemia and, in substantially real-time, to determine indicators of myocardial deformations or other symptoms of similar pathologies.
To make such analysis manageable, functional analysis methods rely on identifying changes in myocardial deformation expressed as strain waveforms derived from ultrasound data. However, movement of the myocardium includes a multitude of individual myocytes working in different directions in layers of the muscle, and timing of each contraction is not simultaneous throughout the heart due to differing electrical and mechanical activation of distinct myocardial regions. Thus, strain waveforms, even for normal regions of myocardium, have a large variability. Since the movement of the myocardium is extremely complex, functional analysis has been limited to merely comparing peaks or crossover points in the waveforms. Hence, only a small fraction of the data contained in the waveforms is considered during analysis.
Predominantly, these parameters are measurements of strain rate or strain magnitude, especially peaks during particular phases of the heart cycle, or alternatively, timings between selected events have been used. Examples of the latter, from both clinical and animal research studies, include the time from the ECG R-wave to peak negative strain and timing to various crossover points as strain or strain rate changes from positive to negative or vice versa. However, the strain waveform is rich in information about local myocardial function throughout the cardiac cycle and limiting the analysis to these particular events disregards a wealth of information that could be indicative of a particular pathology.
Furthermore, to perform the prescribed analysis, clinicians have been required to rely upon experience and observational skills to describe regional myocardial movements and identify segments of the heart that might be normal or ischemic. As such, considerable stress is placed upon the evaluator to simultaneously evaluate the waveforms and identify features within these complex and constantly varying waveforms that may indicate myocardial ischemia or other pathologies. As such, traditional diagnosis methods can be extremely subjective and prone to human error.
Therefore, it would be desirable to have a system and method for analyzing a wide variety of functional imaging data to determine indicators of various pathologies with increased speed and accuracy. For example, it would be desirable to have a system and method to aid in the interpretation and evaluation of a full spectrum of functional imaging data, such as cardiac ultrasound images or entire echocardiogram waveforms, to determine indicators of pathologies such as ischemia.